264 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



DESCRIPTIVE LIST, WITH KEYS. 



KEY TO THE TRIBES. 



Series 1. PANIC AT AE. 



Spikelets with 1 perfect terminal floret (disregarding the few monoecious 

 genera and the staminate and neuter spikelets) and a sterile or staminate 

 floret below, usually represented by a sterile lemma only, one glume sometimes, 

 rarely both glumes, wanting; articulation below the spikelets, either in the 

 pedicel, in the rachis, or at the base of a cluster of spikelets, the spikelets 

 falling entire, either singly, in groups, or together with joints of the rachis; 

 spikelets, or at least the fruits, more or less dorsally compressed (laterally in 

 Lithachne). 



Glumes indurate; fertile lemma and palea hyaline or membranaceous, the 

 sterile lemma like the fertile one in texture. 

 Inflorescence monoecious, the pistillate spikelets below, the staminate above 



on the same rachis 1. TRIPSACEAE (p. 265). 



Inflorescence not monoecious, the fertile spikelets perfect, each usually 

 paired with a sterile spikelet. 

 Spikelets in pairs, one sessile, the other pedicellate (the pedicellate 

 sometimes obsolete) ; lemmas hyaline. 



2. ANDROPOGONEAE (p. 265). 

 Spikelets all alike, solitary or in groups of 2 or 3; lemmas mem- 

 branaceous 3. NAZIEAE (p. 266). 



Glumes membranaceous ; fertile lemma and palea indurate or at least as firm 

 as the glumes ; sterile lemma like the glumes in texture. 

 Fertile lemma and palea scarcety firmer than the glumes. 



4. MELINIDEAE (p. 266). 



Fertile lemma and palea indurate or subindurate, usually much firmer 



than the glumes 5. PANICEAE (p. 267). 



Series 2. POATAE. 



Spikelets 1 to many-flowered, the reduced florets, if any, above the perfect 

 florets (except in Phalarideae; sterile lemmas below as well as above in 

 Uniola) ; articulation usually above the glumes. 



Plants woody, usually arborescent, clambering, or climbing ( scarcely woody 



in Planotia 13. BAMBOSEAE (p. 272). 



Plants herbaceous. 



Spikelets with 2 sterile or rudimentary lemmas unlike and below the 



fertile lemma 7. PHALARIDEAE (p. 269). 



Spikelets without sterile lemmas below the perfect floret (or these rarely 

 present but like the fertile ones). 

 Spikelets articulate below the glumes, 1-flowered, either much com- 

 pressed or if not then unisexual, never in dense spikes ; glumes 



often reduced, sometimes wanting 6. ORYZEAE (p. 269). 



Spikelets articulate above the glumes or, if below, spikelets 2 or more 

 flowered (Notholcus and Sphenopholis) or in dense racemose 

 spikes (Spartina). 

 Spikelets sessile on a continuous rachis, forming spikes (short- 

 pedicellate in Leptochloa and Gouinia). 

 Spikelets on opposite sides of the rachis; spike terminal, 

 single 12. HORDEAE (p. 272). 



